The invention relates to the permanent sealing of underground containment vaults. It is particularly useful in connection with burial vaults of the type containing caskets.
If caskets are buried without being placed in a rigid burial vault, sink holes are often created when the casket decomposes and crushes under the weight of the soil. In order to prevent sink holes, many cemeteries use concrete burial vaults into which the casket is placed for burial. Although concrete burial vaults prevent sink holes, concrete burial vaults are heavy and difficult to use. They are also not particularly effective in preventing the leaching of contaminants from decomposed caskets. Ground water contamination near cemeteries is often a significant problem.
In the past some have attempted to line concrete burial vaults with plastic liners or the like. These techniques have not been terribly effective. Others have attempted to manufacture reinforced plastic burial vaults. Reinforced plastic burial vaults are lightweight, yet can normally be manufactured with appropriate strength to withstand the weight of the soil. Even with reinforced plastic burial vaults, however, moisture can enter through the seam between the cover and the lower compartment. The moisture accelerates decomposition from within the vault.
The invention is a sealed underground containment system that is particularly useful in protecting the environment (including ground water) from contamination due to decomposed contents within the vault. As mentioned, the invention is particularly useful as a burial vault, although it can be used for other kinds of underground containment.
The invention comprises a lower containment compartment and a cover, both preferably made from non-biodegradable plastic such as polyurethane or polypropylene. The container compartment has a bottom wall, and sidewalls and endwalls that extend upwardly from the bottom wall. The lower container compartment includes an upper edge portion that extends peripherally around the upper edge of the container compartment. A fusible element, such as an outwardly extending plastic flange, is provided around the upper edge portion completely around the container compartment. The cover includes a lower edge portion, which likewise has a fusible element extending completely around the lower edge portion of the cover. The fusible element on the cover mates with the fusible element on the container compartment when the cover is placed on the container compartment. The application of heat and pressure to the mated fusible elements welds the fusible elements together, thereby creating a permanent water-tight and air-tight seal. The underground container is thus sealed completely and permanently, thereby better protecting the surrounding environment. When the invention is used in connection with burial vaults, it is particularly effective in slowing decomposition. The rate of decomposition is slowed primarily by preventing water and/or air from penetrating into the vault.
It is preferred to weld the fusible elements together as an integral piece rather than attach the two merely with glue or adhesive. Glue or adhesive often degrades prematurely, especially in the cold, thus leading to premature leakage.
In order to withstand the enormous weight of soil and possibly equipment maneuvering on the ground, it is preferred that the container compartment be comprised of an inner shell glued to an outer shell with foam filling the space therebetween in order to provide structural stability. Preferably, the foam adheres to the inner and the outer shell. It is also preferred that a frame structure be provided between the inner and outer shell for reinforcement. The cover preferably has a similar construction. In one embodiment of the invention, the space between the inner and the outer shell at the bottom wall of the container compartment is left void or empty prior to burial. With this configuration, the vaults are relatively lightweight and can be conveniently moved by a single person. In circumstances where it is important that the vault have significant weight, such as in areas prone to flooding, ballast material such as sand or concrete can be used to fill the void in the bottom wall. In these circumstances, a plug or patch on the outer shell for the bottom wall can be spin-welded to seal the shell after the ballast is added.
In a preferred embodiment of the invention, the mating fusible elements on the upper edge portion of the container compartment and the lower edge portion of the cover comprise flanges that extend outwardly from the edge and completely around the vault (i.e., completely around the container compartment and the cover, respectively). In accordance with the preferred embodiment of the invention, a specialized welding tool is provided for optimum application of heat and pressure to weld the fusible elements together. The preferred welding tool has two sections, each connected by a hinge and a latch to allow the tool to circumvent the vault, and completely cover and engage the mated fusible elements around the periphery of the vault. The welding tool has two heating elements which are separated to allow for insertion of the mated fusible flanges. The heating elements are positioned within a C-shaped bar. An upper air pump is located between an upper extension of the C-shaped bar and an upper heating element, while a lower air pump is located between the lower extension of the C-shaped bar and the lower heating element. Insulation is provided between the air pumps and the respective heating elements.
When the vault is ready to be sealed, a worker places the welding tool around the vault and in engagement with the fusible flanges. The worker then activates the welding tool which heats the heating elements to approximately 400xc2x0-600xc2x0 F. while at the same time provides pneumatic pressure to the air pumps, thereby forcing the heating elements together and causing the fusible flanges to weld together.
In another embodiment, the invention involves the use of a resistance heating element, such as a wire, extending completely around the burial vault and being located between the fusible element for the cover and the fusible element for the containment compartment. When the cover is placed on the containment compartment, electrical power is supplied to the resistance heating element, thereby causing the fusible elements to weld together. The resistance heating element remains an integral component of the vault after sealing.
Other advantages and features of the invention should be apparent to those skilled in the art after inspecting the drawings and the following description thereof.